CVE-2026-6777Network attack vector

Unauthenticated service interruption

Published Apr 21, 2026 · Updated Apr 21, 2026

Uncontrolled resource consumption in Mozilla Firefox and Thunderbird before 150 allows remote attackers to cause a service interrupt via DNS processing. Mozilla has not published the nature of the flaw or the incorrect operation performed on DNS-related input in the Networking: DNS component. Network access without authentication is sufficient; no data disclosure or modification is reported.

CVSS severity5.3
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Mozilla Firefox and Thunderbird before 150 allows remote attackers to cause a service interrupt via DNS processing. Mozilla has not published the nature of the flaw or the incorrect operation performed on DNS-related input in the Networking: DNS component. Network access without authentication is sufficient; no data disclosure or modification is reported.

The record

CVE
CVE-2026-6777
Published
Apr 21, 2026
Updated
Apr 21, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, CWE-400, CWE-352, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-400Uncontrolled Resource Consumption
CWE-352Cross-Site Request Forgery (CSRF)
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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